1. Field of the Invention
The invention generally relates to a device for laterally aligning sheets being fed into a printing press. Such a device can typically have a feeding table, via which the sheets are fed, sheet-by-sheet to front lays, or stops, along with a corresponding side-pull device which can laterally move a respective sheet after the sheet is aligned at the front lay. Such a side-pull device typically will function by means of suction applied to the sheet.
2. Background Information
Known side-pull-type devices, such as those disclosed by German Patents DE 33 11 197 C2 (which corresponds to U.S. Pat. No. 4,591,143) or DE 37 16 085 A1, provide configurations in which the sheets are held by suction onto side-pull rails, or simply onto suction devices, followed by the sheets being conveyed into a respective lateral reference position by moving the side pull-type rails, or the suction devices, respectively. However, it has become apparent that, when aligning heavy sheet material, e.g. cardboard, the suction effect is not always sufficient to ensure an exact lateral movement of the sheet.
In general, the higher the machine speed, the shorter the time remaining for providing a lateral alignment. Moreover, with large sheet formats the mass to be moved is correspondingly larger, and thus considerable friction of the sheet on the feeding table must be overcome. Consequently, within the short time available it is generally not possible to bring such larger, or heavier sheets into the position which is called the reference position. If the frictional resistance between the pull rail and the sheet to be conveyed is increased by certain measures, there is the risk of damage to the sheet surface. As a consequence thereof, machine speeds generally have to be reduced in relation to the weight of the sheets to be printed. Thus, the overall output of the machine can be affected.